DESCRIPTION (abstract): The tumor necrosis factor family of cytokines induces a wide number of biological effects that directly influence cell growth, cell differentiation, and apoptosis. A common feature of this family is the existence of transmembrane receptors with multiple conserved cysteine-rich motifs in the ligand binding domain and a short cytoplasmic domain. The TNF receptor superfamily includes the Fas antigen, two TNF receptors, CD40, CD30, and the p 75 neurotrophin receptor. Several of these receptors contain a death domain sequence which is responsible for transmitting cell death signals. These receptors contain a death domain sequence which is responsible for transmitting cell death signals. These receptors can recruit and bind adapter molecules, which in turn associate with cytoplasmic proteins associated with caspase activation and serine/threonine protein kinases activities. In this renewal application, we will focus on an adapter molecule, SC-1, a novel zinc finger protein which belongs to a family of genes implicated in tumor progression. SC-1 was first identified as a p75 receptor binding protein; subsequent studies indicate that it is associated with growth arrest events. The further characterization of this zinc finger protein with the actions of TNF receptor members will likely yield additional mechanisms concerning cell proliferation. These studies will provide insight into mechanisms responsible for cytokine actions during inflammation, injury and disease states.